An in-vehicle cutoff device includes a first input terminal, a first output terminal, a first conductor wire, a second input terminal, a second output terminal, a second conductor wire, a first current detector capable of detecting a current flowing through the first conductor wire or the second conductor wire, a second current detector capable of detecting a current flowing through the first conductor wire or the second conductor wire, a pyrotechnic circuit breaker capable of irreversibly disconnecting the first conductor wire, and controller capable of controlling a cutoff operation of the pyrotechnic circuit breaker in response to the detected currents. The controller causes the cutoff operation of the pyrotechnic circuit breaker to perform the cutoff operation when both of a first current value generated based on a first detection signal and a second current value generated based on the second detection signal exceed an overcurrent threshold.